[Bob Carriere]

In similar circumstances....... we use the oxy-acet to heat up the casting to a pale cherry red...... than with a handy dandy impact screw driver start impacting the screw head. The screws can be hard rusted to the point of shearing the flat end of the screw dirver attachements..... but they sell spares.

As mentioned if it does not work at first quench with water....let it sit.... repeat heat process.

Prefer it to drilling heads off 10 to 1.

Another way would be to grind some clean shiny meatl on the screw head and weld a 3/8 nut on the head using the mig welder....... let the nut glow red....wait for the heat to bleed into the casting..... when parlty cool torque gently back and forth until loose.... if nut breaks off weld another one.....

Good luck.

Bob